Fisheries Gear
Basic fishing technology - the use of
hook and line, or nets - to catch fish, is as old as human
civilization itself. Advances in technology have vastly
improved the ability to find fish, process and store fish,
and transport fish and seafood products. Technology has
also improved our ability to target individually sized
fish, reduce the impacts of bycatch, and reduce impacts
of gear on the ocean environment. The following descriptions
explain how some commonly used fishing vessels work.
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Gillnetters are
commonly deployed in Pacific Salmon fisheries, primarily
sockeye, chum and Coho. They work by setting curtain-
like nets perpendicular to the direction which the
salmon are traveling. The net has a float line (corkline)
on the top and a weighted line (leadline) on the bottom.
The mesh is designed to be just large enough to allow
the salmon to become entangled at their gills.
Gillnet
vessels are typically around 30' to 40' long. They
are easily recognized by the hydraulic-powered drum
onto which the net is rolled. The drum can be located
on the back or the front of the vessel. |
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Longliners can
either target on bottom fish like lingcod, halibut,
pacific cod and sablefish, or pelagic fish like swordfish.
In bottom longlining, a line, up to a mile in length,
is anchored on the seafloor with buoy lines marked
with flags at either end. The line can have up to a
thousand baited hooks attached to leaders, called gangions,
and are deployed for up to 24 hours, depending on the
fishery. Pelagic longliners work the same way but with
the gear suspended in the water column held up with
floats.
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Purse Seiners like
this one catch schooling fish like salmon, menhaden
or herring by encircling them with a long net and
drawing (pursing) the bottom closed to capture the
fish within. Seiners can be recognized by their long,
clean decks, large boom and power block, net stacked
on back, and the power skiff used to help maneuver
the net. The skiff is often seen riding "piggyback" aboard
the vessel's stern while traveling.
Larger Purse seiners are used in tuna fisheries
and are often at sea for several weeks at a time.
Large tuna purse seiners may even have helicopters
on board to transport crew and to spot large schools
of fish.
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Larger Purse seiners like
this one are used in tuna fisheries and are often at
sea for several weeks at a time. Large tuna purse seiners
may even have helicopters on board to transport crew
and to spot large schools of fish. Purse seiners catch
schooling fish like salmon, menhaden or herring by
encircling them with a long net and drawing (pursing)
the bottom closed to capture the fish within. Seiners
can be recognized by their long, clean decks, large
boom and power block, net stacked on back, and the
power skiff used to help maneuver the net. The skiff
is often seen riding "piggyback" aboard the
vessel's stern while traveling.
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A trawler is
a vessel that drags a funnel-shaped net through water
to harvest fish or shrimp. The net is wide at the
mouth and tapers back to a narrow cod end that collects
the catch. The average bottom trawl opening is 40
to 60 feet wide and 8 to 10 feet tall. Bottom trawlers
usually tow their nets at 1 to 2 knots on or above
the ocean floor. Fishermen tow midwater trawls faster
to catch faster-swimming schooling fish. Trawlers
have a large metal trawl door that acts like a foil
in the water pulling the net open when the net is
deployed. The nets are usually hauled aboard on a
ramp located at the stern end of the boat with the
help of heavy-duty winches. Older trawlers without
inclined ramps haul their nets over the sides using
a haul line and a block on an overhead boom to bring
in the cod end of the net.
Trawlers catch a wide variety of fish and shrimp
including rockfish, cod, sablefish (black cod), ocean
perch, flounder, and sole. Trawls can be designed
to catch particular groups of fish through adaptations
to the mesh size of the net.
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Large trawlers work
by dragging a net through the water catching schooling
fish like walleye pollock. These boats can be up to
600 feet in length and can even have entire fish processing
facilities on board. Most trawl nets have "doors" large
metal or wood devices that keep the net open as it
moves through the water. Some have a heavy weighted
bottom line with wheels to help the net move along
the seafloor. The end of the net, the "cod end" is
like a large pocket that holds the captured fish. Mesh
size in the net and cod end determine what size fish
are caught and what size gets away.
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Troll vessels catch
salmon, principally chinook, coho and pink salmon by "trolling" bait
or lures. Usually this means four to six main wire
lines are fished at a time, each with a 50 lb. lead "cannon
ball" weight and between eight to twelve nylon
leaders spaced out along its length. Each nylon leader
contains a lure or baited hook.
Trollers come
in a variety of lengths and styles, but can be largely
recognized by the long mast poles that are used to
relay the wire lines out into the water.
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By far the most common type of fishing
vessel is the sport fishing boat.
These boats can be spotted in most any marina or harbor
in the U.S. Sport boats typically rely on hook and
line fishing but can also be used to deploy traps
or nets. There are an estimated 17.7 million sport fishing
boats in the United States. Recreational anglers
take an average of 89 million fishing trips per year.
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NOAA maintains a fleet of 18 fisheries
and ocean science vessels to carry
out a number of science objectives. These vessels are
deployed around the world and each is specifically
fitted to the type of research it does. New vessels
like the "Oscar
Dyson" have been designed to assist fisheries
scientists with state-of-the-art acoustic quieting
technology, which enables NOAA scientists to monitor
fish populations without altering their behavior. Oscar
Dyson's capability to conduct both fishing and
oceanographic research is unique among research vessels
and a value to its users.
For more information
on the NOAA Fleet, please visit
us online.
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